What Does It Take to Run a Multi-Tenant GB200 or GB300 GPU Service Reliably?
Introduction Once an operator decides to offer rack-scale GPUs as a shared service, the question becomes, "How do we ensure tenant isolation?" rather than, "Can we offer tenant isolation?" NVL72 systems interconnect 72 Blackwell GPUs using NVLink, and racks are interconnected using an InfiniBand scale-out fabric. Isolation is needed at both the interconnect and fabric level, and both have to agree. Here we focus on the interconnect side of this problem. Why Isn't a VLAN Enough Here? As NVLink doesn’t follow traditional Ethernet behaviors, methods used to isolate Ethernet tenants do not work here. Isolation needs to occur in the fabric. Full NVLink bandwidth is preserved in the hardware-level GPU partition. There is no connectivity to other partitions. How Do Single-Rack and Multi-Rack Tenants Differ? In a single rack, a tenant requires NVLink partitioning. A tenant spanning multiple racks requires NVLink partitions and a private InfiniBand partition spanning the...